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April, 04/27/2015
Events and times subject to change

April 27, 2015 Monday 10:00 AM  +
Meyer 721
Other Physics Department Events (other)


Marco Tavora
New York University

Oral Defense:
Prethermalization, Universal Scaling at Macroscopic Short Times, and Thermalization Following a Quantum Quench



April 27, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag
Maryam Modjaz
NYU

The Progenitors of Gamma-Ray Bursts



April 27, 2015 Monday 3:00 PM  +
Meyer 6th Floor Conference Room
Soft Condensed Matter Seminars (csmr)


Nicholas Schade
Harvard University

Self-Assembly of Plasmonic Nanoclusters for Optical Metafluids

Metamaterials are synthetic substances designed to exhibit physical properties not found in naturally occurring materials, such as refractive index close to or less than zero. They have seen an explosion of interest in the scientific community ever since John Pendry's prediction (Phys. Rev. Lett. 85, 18, 2000) that a material with a negative refractive index could be used for imaging with unlimited resolution. Fabricating these materials for optical frequencies is challenging, however, since they require circuitry smaller than the wavelength of light that they are designed to manipulate, and conventional nanofabrication techniques cannot produce the necessary structures, such as tetrahedral sphere clusters. One solution to this problem is colloidal self-assembly, a process in which nanoparticles are mixed in a fluid and spontaneously organize into larger structures. I will demonstrate that in a mixture of two types of particles which can bind irreversibly to one another, the diameter ratio controls the size distribution of self-assembled clusters. Surprisingly, at a diameter ratio of 2.45, tetrahedral clusters form in 90% yield in our experiments. We explain how this occurs with a nonequilibrium "random parking" model, which predicts that 100% yield of tetrahedra is possible in principle. I will show how we are using this for the self-assembly of plasmonic resonators for metafluids.


April 28, 2015 Tuesday 2:00 PM  +
Meyer 611
Hard Condensed Matter Seminars (hcmp)


Efrat Shimshoni
Bar-Ilan University

Collective Edge Modes Near the Onset of a Graphene Quantum spin Hall State

Graphene subject to a strong, tilted magnetic field exhibits an insulator-metal transition tunable by tilt-angle, which is attributed to the transition from a canted antiferromagnetic (CAF) to a ferromagnetic (FM) bulk state at filling factor \nu=0. We develop a theoretical description for the spin and valley edge textures in the two phases, and the implied evolution in the nature of edge modes through the transition. In particular, we show that the CAF has gapless neutral modes in the bulk, but supports gapped charged edge modes constructed by the binding of a vortex (meron) in the bulk state to a spin twist at the edge. The energy gap of this edge mode is therefore dictated by the bulk spin stiffness. At the transition to the FM state where the latter vanishes, the charged edge modes become gapless and are smoothly connected to the helical edge modes of the FM state. We further discuss possible experimental consequences.


April 29, 2015 Wednesday 10:00 AM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

PhD defense
Daniel Foreman-Mackey
NYU

Exoplanets TBA



April 29, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Sean Carroll
Caltech

Quantum Mechanics and Cosmology in Very Large Universes

Modern physics frequently envisions scenarios in which the universe is very large indeed: large enough that any allowed local situation is likely to exist more than once, perhaps an infinite number of times. Multiple copies of you might exist elsewhere in space, in time, or on other branches of the wave function. Such duplication is inevitable the Everett (Many-Worlds) formulation of quantum mechanics, and has a beneficial effect: it leads to a simple derivation of the Born Rule for quantum probabilities. Duplication can be a bad thing in cosmology, where it leads to Boltzmann Brains and the cosmological measure problem. An improved understanding of quantum fluctuations shows that Boltzmann Brains can be easily avoided if they don’t correspond to decoherent branches of the wave function.


April 29, 2015 Wednesday 2:00 PM  +
Meyer 6th Floor Conference Room
Soft Condensed Matter Seminars (csmr)


Dennis Discher
University of Pennsylvania

How Long Is All The DNA in Your Body and How Do You Physically Protect It?



April 30, 2015 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Marc Kamionkowski

Inflation: There's Room at the Bottom

The idea that the Universe underwent a period of superluminal expansion, known as inflation, has gained considerable traction with the advent of precise measurements over the past decade+. One of the key predictions of inflation is a spectrum of primordial density fluctuations that remains nearly scale-invariant over 15-25 decades in distance scale. The near scale-invariance of primordial perturbations over the roughly 3 decades over which the spectrum has been measured so far remains one of the theory's greatest successes. Still, it is interesting to think whether that spectrum can be measured over the remaining 12-22 decades, all of it at distance scales smaller than those that can be probed by the cosmic microwave background or galaxy surveys. I will discuss some ideas for accessing these smaller scales.


May 1, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Sarbani Basu
Yale University

Journeying to the center of stars

Helioseismology, the seismic study of the Sun, has allowed us to probe the structure and dynamics of the solar interior with unprecedented accuracy. Helioseismic data have also allowed us to study properties of stellar matter. NASA's Kepler mission has allowed us to undertake seismic studies of other stars. While the field is not yet fully developed and we are still learning the best way to analyze the data, asteroseismic studies of stars has already produced exciting results. In this talk I shall review what asteroseismology is, how we interpret asteroseismic data, and then talk about some of the exciting results obtained with data from Kepler.


May 1, 2015 Friday 4:00 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Other
Maryam Modjaz
NYU

(SPS) Undergrad Lectures



May 4, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag



May 6, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Daniel Harlow
Princeton

TBA



May 6, 2015 Wednesday 2:00 PM  +
Meyer 6th Floor Conference Room
Soft Condensed Matter Seminars (csmr)


Edward Lyman

Coexisting Fluid Phases, Cholesterol, and Cell Signaling

The plasma membrane of a eukaryotic cell is a complex mixture of some 800 lipids and assorted proteins, all anchored to the actin cytoskeleton. The plasma membrane is known to be laterally heterogeneous, and this heterogeneity is believed to have a functional role, modulating cellular repsonses by spatiotemporal control of signaling proteins. Cholesterol is the most abundant component (by mole percent) in the membrane, and is known to control membrane heterogeneity in model systems. I will present a new view of the nanoscale structure and dynamics of cholesterol rich, lipid bilayer liquid phases, obtained through a combination of NMR, neutron scattering, and molecular simulation on special purpose hardware. The transport of lipids is observed to be strongly subdiffusive on biologically relevant timescales. A possible functional role for subdiffusive transport of membrane components will be proposed, within the context of arguments put forth by Berg and Purcell nearly 40 years ago.


May 7, 2015 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Ivan Schuller
UCSD

Why Physics:
Beyond Atom Bombs and Big Bangs

Physics has evolved as a discipline by asking fundamental questions about the universe. While some of the questions regarding the beginning and end of the universe are well known and publicized, what it is not commonly recognized that asking fundamental questions at or above the atomic level have lead to major scientific revolutions. I will describe in this talk how condensed matter physics at sizes approaching atomic dimensions (“nanostructures”) is revolutionizing basic concepts in physics, chemistry and biology. When the size of a material approaches that of an atom its properties change radically. I will describe several exciting and new directions in the field of oxides, spintronics, and organic materials. The new physics evolving from this research may lead to novel applications which cannot be predicted at present, but which surely will revolutionize electronics, medicine, and engineering. This colloquium, accessible to non-experts, will be dedicated to highlighting the recent scientific advances in the field and possible new directions.
Work supported by the US Air Force Office of Scientific Research, Department of Energy and the National Science Foundation.


May 8, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Erik Tollerud
Yale University

Local Dwarf Galaxies and Near-Field Cosmology in ΛCDM

Dwarf galaxies are a frontier for new discoveries in both galaxy formation and cosmology. I will discuss work centered around connecting LCDM and its predictions to observations of dwarf galaxies at three different scales of "dwarf". I will discuss the Milky Way and M31's satellites and both solutions and lingering troubles with their abundances and scalings. I will also describe efforts to use these scalings in conjunction with simulations to constrain if and how the satellite's baryons are strongly influenced by their hosts. Finally, I will describe searches for comparable satellites beyond the Local Group, and compare their abundances and properties to straightforward LCDM expectations.


May 8, 2015 Friday 4:00 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Other
Paul Chaikin
NYU

(SPS) Undergrad Lectures



May 11, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag



May 11, 2015 Monday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Thesis Defense
Victor Gorbenko
NYU

TBA



May 12, 2015 Tuesday 11:00 AM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Informal Astro Talk
Shadab Allam
Carnegie Mellon

Redshift Space Distortions in BOSS

TBD.


May 13, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Kristan Jensen
Stony Brook

TBA



May 13, 2015 Wednesday 2:00 PM  +
Meyer 6th Floor Conference Room
Soft Condensed Matter Seminars (csmr)


Alexander Sodt

TBA



May 15, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Katherine Deck
Caltech

exoplanet dynamics TBD



May 18, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag



May 19, 2015 Tuesday 11:00 AM  +
Meyer 6th Floor Conference Room
Physics Colloquia (colloquia)


Jacqueline Bloch
Laboratoire de Photonique et de Nanostructures, LPN/CNRS

Manipulating Polariton Quantum Fluids in Semiconductor Microcavities

At the frontier between non-linear optics and Bose Einstein condensates, semiconductor microcavities have opened a new research field, both for fundamental studies of bosonic quantum fluids in a driven dissipative system, and for the development of new devices for all optical information processing. Optical properties of semiconductor microcavities are governed by bosonic quasi-particles named cavity polaritons, which are light-matter mixed states. Cavity polaritons propagate like photons, but interact strongly with their environment via their matter component. Patterning of semiconductor microcavities on a micron scale allows confining polaritons in photonic circuits or in lattices.
After a general introduction on cavity polaritons, I will illustrate the diversity of physical problems that can be addressed in this non-linear photonic system using patterned microstructures.I will show that taking advantage of the giant non-linearities induced by polariton interaction it is possible to realize photonic circuits in which coherent polaritons are propagated and optically manipulated.
The second part of the talk will be dedicated to the physics of polaritons in lattices. I will show that we can implement complex Hamiltonians and thus develop a new platform for quantum emulation. For instance, we have demonstrated a fractal energy spectrum for polaritons by engineering a quasi-periodic lattice. It becomes possible to explore the physics of non-linear wavepackets in such complex environment. Polaritons are also very promising for the investigation of graphene physics using honeycomb lattices. For instance, Dirac cones are directly imaged in the polariton far field emission. Finally we recently fabricated lattices holding non dispersive bands. In such flat bands, kinetic energy frustration dramatically modifies the spontaneous spatial coherence of polariton condensates.
[1] Spontaneous formation and optical manipulation of extended polariton condensates, E. Wertz, et al., Nat. Phys. 6, 860 (2010)
[2] Realization of a double barrier resonant tunneling diode for cavity polaritons, H-.S. Nguyen et al., Phys. Rev. Lett. 110, 236601 (2013)
[3] All-optical phase modulation in a cavity-polariton Mach-Zehnder interferometer, C. Sturm et al., Nature Commun. 5, 3278 (2014)
[4] Fractal energy spectrum of a polariton gas in a Fibonacci quasi-periodic potential, D. Tanese et al., Phys. Rev. Lett. 112, 146404 (2014)
[5] Direct observation of Dirac cones and a flatband in a honeycomb lattice for polaritons, T. Jacqmin et al., Phys. Rev. Lett. 112, 116402 (2014)
[6] Spin-Orbit Coupling for Photons and Polaritons in Microstructures, V.G. Sala et al., Phys. Rev. X 5, 011034 (2015)


May 20, 2015 Wednesday 3:00 PM  +
Meyer 6th Floor CSMR Area
Other Physics Department Events (other)

Physics Department Graduation Party



May 22, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Informal Astro Talk
Lara Nava
Hebrew Univ.

High-energy emission from Gamma-Ray Bursts: advancing our knowledge on GRBs and relativistic shocks through modeling of afterglow radiation

The physical origin of the temporally extended (~10^2 sec) high-energy emission (0.1-100 GeV) detected from Gamma-Ray Bursts by the Fermi/LAT instrument has not yet been completely understood. I present the evidences in favour of the external shock scenario, where the LAT emission is interpreted as radiation from electrons accelerated at the relativistic shock developed in interactions with the external medium. I show that the modelling of LAT lightcurves not only reveals specific features consistent with the proposed interpretation, but also has predictive power on parameters entering the shock physics and the physics of the prompt emission mechanism. Extension of this study to include X-ray and optical afterglow data reveals that broadband modelling within the external shock scenario is always successful for the sample of GRBs with LAT temporally extended emission (10 events), and leads to two possibilities: either the X-ray emitting electrons (unlike the GeV emitting electrons) are in slow cooling regime or ii) the X-ray flux is strongly suppressed by Compton cooling, whereas, due to Klein-Nishina, the suppression is negligible at GeV energies. In both cases the LAT flux is a more robust proxy for the blastwave energy than the X-ray flux. On average, both cases require weak magnetic fields and relatively large blastwave energies. These large energies left in the blastwave reduce the efficiency requirements on the still uncertain mechanism responsible for prompt emission. Finally, I present preliminary results on the consistency of the external shock interpretation with the detection rate of high-energy emission from GRBs.


May 27, 2015 Wednesday 2:00 PM  +
Meyer 6th Floor Conference Room
Hard Condensed Matter Seminars (hcmp)


Ignace Jarrige
Brookhaven National Laboratory

Group Leader, Soft Inelastic X-ray Scattering Beamline (SIX)



May 29, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Matthew Turk
NCSA

Astrophysical Inquiry: A Disrupted Market

The availability of low-cost hardware, high-functionality software, and the plethora of methods for acquiring, inspecting, analyzing and sharing data has changed the way individual researchers as well as entire communities -- such as astronomy and astrophysics -- understand and interact with their data. Processes that used to be hard are now trivial; processes that used to be impossible are now necessary. Drawing on examples from computational astrophysics and cosmology, I will describe how the commodity market for data-related services has changed the needs of the scientific community, and how this can be leveraged in the future to develop advanced, useful, and forward-thinking technologies to transform the way researchers interact with data.


September 18, 2015 Friday 11:00 AM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Informal Astro Talk
Matteo Biagetti
University of Geneva

TBA